Due to the advancement of current electronic and information technologies, various communication and information products have been developed to meet daily requirements. Among the communication products, flange-mount SMA connectors are extensively used around the world for many high-frequency devices. The connectors are normally used at the input and output ports of the devices to provide transitions between a coaxial line and a planar transmission line in order to facilitate the testing of the devices.
Another application is the connection between different transmission lines, which is usually required in system integration. For example, connections between a coaxial line and a microstrip line; a coaxial line and a coplanar waveguide; a coaxial line and a waveguide; and a waveguide and a microstrip line, wherein the connection between the coaxial line and the microstrip line is the most common combination. To achieve successful signal transmission between these two transmission lines with minimum insertion loss, the designs of their transitions become very important.
With reference to FIGS. 1A and 1B for a schematic view of a conventional flange-mount SMA connector and a schematic view of a conventional transition between a coaxial line and a microstrip line using such SMA connector, respectively, the conventional flange-mount SMA connector 100 is a coaxial connector, comprising an outer conductor 111, a mounting wall 120, a center conductor 130, and a dielectric material 122. The transition is mainly used for high-frequency test setups or the input and output ports of high-frequency devices for signal transmission between the coaxial line (not shown in the figures) and the microstrip line 140. This conventional transition requires the center conductor 130 of the flange-mount SMA connector 100 connected to the signal line 142 on the substrate 143 of the microstrip line 140, and then needs the outer conductor 111 and the mounting wall 120 of the coaxial connector electrically connected to the ground plane 141 of the microstrip line 140 to accomplish the signal transmission between the two transmission lines, as shown in FIG. 1B.
With reference to FIGS. 2A and 2B for the electric field and magnetic field distributions of a coaxial line and a microstrip line, respectively, the differences in the electric field and magnetic field distributions of the two transmission lines result in insertion loss at the transition between the two transmission lines. The loss becomes severe as the operating frequency increases and, thus, constrains the 1-dB passband of the conventional transition.
Therefore, it is important for the present invention to disclose a connector capable of reducing the insertion loss caused by the change of the electric field and magnetic field distributions of the two transmission lines at the transition.